Pneumatic tool

ABSTRACT

A pneumatic tool comprises a housing, a cylinder and a pneumatic assembly. The housing includes a compartment, an air entrance channel interconnecting with the compartment, and an air exit channel interconnecting with the compartment. The air exit channel includes an air incoming end, an air outgoing end, and a flow-guiding incline disposed on one side of the compartment, which faces the cylinder, and connected with the rim of the air exit channel partially or completely. The cross section of the air incoming end is larger than the cross section of the air outgoing end. 
     The air incoming end guides the high-speed and high-pressure air to the air exit channel to increase the flow rate at which the high-speed and high-pressure air flows out of the air exit channel. Thereby is solved the operational abnormalities caused by that the conventional pneumatic polishing-grinding machine cannot fully exhaust high-speed and high-pressure air.

FIELD OF THE INVENTION

The present invention relates to a pneumatic tool, particularly to a pneumatic tool whose air exit channel includes an air incoming end with a cross section larger than the cross section of the air outgoing end to increase the flow rate of the high-speed and high-pressure air.

BACKGROUND OF THE INVENTION

A pneumatic grinding tool is a handheld grinder driven by high-speed and high-pressure air to polish or grind and sand the surface of a metallic or wooden workpiece.

A Taiwan patent No. M295556 disclosed a pneumatic polishing-grinding machine, which comprises a housing, a cylinder, a transmission shaft, a grinding wheel, and a pneumatic wheel. The housing has a compartment, an air entrance channel and an air exit channel. The air entrance channel and the air exit channel interconnect with the compartment. The cylinder is disposed inside the compartment. The cylinder has an air chamber, an air inlet hole interconnecting with the air chamber and the air entrance channel, and an air outlet hole interconnecting with the air chamber and the compartment. The transmission shaft extends from the air chamber to the exterior of the housing. The grinding wheel is installed on one end of the transmission shaft, which is far away from the housing. The pneumatic wheel is installed on another end of the transmission shaft, which is inside the air chamber.

While the pneumatic polishing-grinding machine operates, high-speed and high-pressure air flows from the air entrance channel to the air chamber and drives the pneumatic wheel to rotate. The rotating pneumatic wheel further drives the grinding wheel to rotate via the transmission shaft. The user moves the rotating grinding wheel to contact a metallic or wooden workpiece for polishing or grinding the workpiece. Meanwhile, the high-speed and high-pressure air flows from the air chamber to the compartment via the air outlet hole and then flows from the compartment to the air exit channel. Via sucking and exhausting high-speed and high-pressure air persistently, the pneumatic polishing-grinding machine can drive the grinding wheel to rotate continuously and enable the user to grind workpieces.

However, the inner wall of the compartment is normally a round curved face. Thus, while the pneumatic polishing-grinding machine operates, the round curved face of the inner wall of the compartment makes the high-speed and high-pressure air circulate inside the compartment. The high-speed and high-speed air circulating inside the compartment would back pressurize and block the high-speed and high-pressure air coming from the air entrance channel. The back pressure and blocking action may make the pneumatic polishing-grinding machine unable to drive the pneumatic wheel normally. Thus is decelerated the grinding wheel and affected the grinding effect.

SUMMARY OF THE INVENTION

The primary objective of the present invention is to solve the operational abnormalities caused by the phenomenon that the conventional pneumatic polishing-grinding machine cannot fully exhaust high-speed and high-pressure air.

To achieve the abovementioned objective, the present invention proposes a pneumatic tool, which comprises a housing, a cylinder, and a pneumatic assembly. The housing includes a compartment, an air entrance channel interconnecting with the compartment, and an air exit channel interconnecting with the compartment. The air exit channel includes an air incoming end and an air outgoing end. The cylinder includes an air chamber for accommodating the pneumatic assembly, and an air inlet hole interconnecting with the air chamber and disposed corresponding to the air entrance channel, and an air outlet hole interconnecting with the air chamber and the compartment. The present invention is characterized in that the air exit channel includes a flow-guiding incline disposed on one side of the compartment, which faces the cylinder, and connected with the entire rim or a part of the rim of the air exit channel, and that the cross section of the air incoming end is larger than the cross section of the air outgoing end.

In one embodiment, the curvature of the flow-guiding incline gradually increases from one side thereof, which is far away from the air exit channel, toward the air exit channel. In one embodiment, the flow-guiding incline is connected with a part of the rim of the air exit channel, and the air exit channel further includes a blocking member disposed at a region of the air exit channel, which is not connected with the flow-guiding incline, wherein the flow-guiding incline and the blocking member are respectively disposed at two opposite sides of the air exit channel.

In one embodiment, the pneumatic assembly includes a pneumatic wheel, a transmission shaft connected with the pneumatic wheel and penetrating the housing, and an application tool installed at one end of the transmission shaft, which is far away from the housing.

In one embodiment, the application tool is a grinding wheel, a polishing wheel, or a sanding wheel pad.

In one embodiment, the axis of the application tool coincides with the axis of the transmission shaft.

In one embodiment, the axis of the application tool separates from the axis of the transmission shaft.

The present invention features that the flow-guiding incline is connected with the entire rim or a part of the rim of the air exit channel and that the cross section of the air incoming end is larger than the cross section of the air outgoing end, whereby the pneumatic tool of the present invention can use the air incoming end to guide the high-speed and high-pressure air to the air exit channel, and whereby the high-speed and high-pressure air can be persistently supplied from the air entrance channel to the air chamber to drive the pneumatic assembly to operate smooth, wherefore the present invention can solve the operational abnormalities caused by the phenomenon that the conventional pneumatic polishing-grinding machine cannot fully exhaust high-speed and high-pressure air.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view schematically showing a pneumatic tool according to one embodiment of the present invention;

FIG. 2 is an exploded view schematically showing a pneumatic tool according to one embodiment of the present invention;

FIG. 3 is a sectional view schematically showing a pneumatic tool according to a first embodiment of the present invention;

FIG. 4 is a local top sectional view schematically showing a pneumatic tool according to the first embodiment of the present invention;

FIG. 5 is a local top sectional view schematically showing a pneumatic tool according to a second embodiment of the present invention;

FIG. 6 is a local top sectional view schematically showing a pneumatic tool according to a third embodiment of the present invention; and

FIG. 7 is a local top sectional view schematically showing a pneumatic tool according to a fourth embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The technical contents of the present invention will be described in detail in cooperation with the drawings.

Refer to FIG. 1 to FIG. 3. The present invention proposes a pneumatic tool, which comprises a housing 1, a cylinder 2, and a pneumatic assembly 3. The housing 1 includes a compartment 11, an air entrance channel 12, and an air exit channel 13. The air entrance channel 12 and the air exit channel 13 interconnect with the compartment 11. The air exit channel 13 includes an air incoming end 131, an air outgoing end 132, and a flow-guiding incline 133. The air incoming end 131 and the air outgoing end 132 are respectively defined by the two opposite terminals of the air exit channel 13. The cross section of the air incoming end 131 is larger than the cross section of the air outgoing end 132. The flow-guiding incline 133 is disposed on one side of the compartment 11, which faces the cylinder 2, and connected with the entire rim or a part of the rim of the air exit channel 13. The curvature of the flow-guiding incline 133 gradually increases from one side thereof, which is far away from the air exit channel 13, toward the air exit channel 13, as shown in FIG. 4 and FIG. 5. As shown in FIG. 4, in the embodiment that the flow-guiding incline 133 is connected with the entire rim of the air exit channel 13, the air incoming end 131 is defined by the border of the junction of the flow-guiding incline 133 and the compartment 11. In such a case, the air incoming end 131 is formed into an expanded hole by the annular expansion of the flow-guiding incline 133. As shown in FIG. 5, in the embodiment that the flow-guiding incline 133 is connected with a part of the rim of the air exit channel 13, the flow-guiding incline 133 is extended from a region of the compartment 11, which is far away from the air exit channel 13, to the air exit channel 13; the air incoming end 131 is defined by the border of the junction of the flow-guiding incline 133 and the compartment 11 and the border of the junction of the air exit channel 13 and the compartment 11. In such a case, the air incoming end 131 is formed into a flow-guiding chute by the arc extension of the flow-guiding incline 133.

Refer to FIG. 1 to FIG. 3 again. The cylinder 2 includes an air chamber 21, an air inlet hole 22, and an air outlet hole 23. The volume of the air chamber 21 is smaller than the volume of the compartment 11. The air chamber 21 interconnects with the air inlet hole 22 and the air outlet hole 23. The pneumatic assembly 3 includes a pneumatic wheel 31, a transmission shaft 32, and an application tool 33. The application tool 33 may be a grinding wheel (disc), a polishing wheel (disc), or a sanding wheel pad.

As shown in FIG. 1 to FIG. 5, in assembling the housing 1, the cylinder 2, and the pneumatic assembly 3, the cylinder 2 is disposed inside the compartment 11 with an air flow gap 4 formed between the outer rim of the cylinder 2 and the inner wall of the compartment 11. The air flow gap 4 not only involves the area neighboring the air outlet hole 23 (as shown in FIG. 3) but also includes the annularity-like space between the cylinder 2 and the compartment 11. Besides, the air inlet hole 22 is connected with the air entrance channel 12 so that the air entrance channel 12 can interconnect with the air chamber 21. Further, the air outlet hole 23 makes the air chamber 21 interconnect with the compartment 11. The pneumatic wheel 31 is disposed inside the air chamber 21. The transmission shaft 32 is connected with the pneumatic wheel 31 and penetrates the housing 1. The application tool 33 is assembled to one end of the transmission shaft 32, which protrudes from the housing 1. In the present invention, the axis of the application tool 33 may coincide with or separate from the axis of the transmission shaft 32. Thereby is completed the assemblage of the housing 1, the cylinder 2, and the pneumatic assembly 3.

In application, the air entrance channel 12 is connected with an air compressor (not shown in the drawings), and the air compressor supplies high-speed and high-pressure air to drive the pneumatic tool. Refer to FIG. 2 to FIG. 5 again. The high-speed and high-pressure air flows from the air entrance channel 12 and the air inlet hole 22 to the air chamber 21 and drives the pneumatic wheel 31 to rotate, and the rotating pneumatic wheel 31 further drives the application tool 33 to rotate through the transmission shaft 32. The user moves the rotating application tool 33 to contact a workpiece (not shown in the drawings) to undertake grinding or polishing. After driving the pneumatic wheel 31, the high-speed and high-pressure air flows from the air chamber 21 through the air outlet hole 23 to the air flow gap 4 and then flows from the air flow gap 4 to the air exit channel 13. As the high-speed and high-pressure air is persistently exhausted from the air exit channel 13, the air compressor can keep on supplying the high-speed and high-pressure air to the compartment 11 to continuously drive the pneumatic wheel 31 to rotate. Thereby, the user can continuously grind or polish workpieces.

It should be particularly mentioned: the present invention is characterized in that the cross section of the air incoming end 131 is larger than the cross section of the air outgoing end 132. While the high-speed and high-pressure air flows from the air flow gap 4 to the air exit channel 13, the air incoming end 131 guides the high-speed and high-pressure air to the air exit channel 13, whereby is increased the flow rate at which the high-speed and high-pressure air flows out of the air exit channel 13, and whereby the air compressor can persistently supply the high-speed and high-pressure air to the air chamber 21 through the air entrance channel 12 to drive the pneumatic assembly 3 to operate smooth. Therefore is solved the operational abnormalities caused by the phenomenon that the conventional pneumatic polishing-grinding machine cannot fully exhaust high-speed and high-pressure air.

The flow-guiding incline 133 forms the air incoming end 131 into an expanded hole (as shown in FIG. 4) or a flow-guiding chute (as shown in FIG. 5) in different embodiments. In one embodiment, the flow-guiding incline 133 further makes the air incoming end 131 have the features of an expanded hole and a flow-guiding chute simultaneously (as shown in FIG. 6). Thereby, the air incoming end 131 of the present invention can guide the high-speed and high-pressure air to the air exit channel 13 and increase the flow rate at which the high-speed and high-pressure air flows out of the air exit channel 13. Therefore, the present invention can fully exhaust the high-speed and high-pressure air out of the air exit channel 13.

In the embodiment that the flow-guiding incline 133 is connected with a part of the rim of the air exit channel 13 and the air incoming end 131 includes the feature of a flow-guiding chute, the air exit channel 13 may further include a blocking member 134 disposed at a region of the air exit channel 13, which is not connected with the flow-guiding incline 133, as shown in FIG. 7. Thereby, the blocking member 134 can block the high-speed and high-pressure air guided by the flow-guiding incline 133 and direct the high-speed and high-pressure air to the air exit channel 13. In detail, the flow-guiding incline 133 and the blocking member 134 are respectively disposed at two opposite sides of the air exit channel 13; the flow-guiding incline 133 guides the high-speed and high-pressure air to the blocking member 134, and the blocking member 134 directs the high-speed and high-pressure air to the air exit channel 13. 

What is claimed is:
 1. A pneumatic tool, comprising a housing, a cylinder and a pneumatic assembly, wherein the housing includes a compartment, an air entrance channel interconnecting with the compartment, and an air exit channel interconnecting with the compartment, and wherein the air exit channel includes an air incoming end and an air outgoing end, and wherein the cylinder includes an air chamber for accommodating the pneumatic assembly, an air inlet hole interconnecting with the air chamber and disposed corresponding to the air entrance channel, and an air outlet hole interconnecting with the air chamber and the compartment, and wherein the pneumatic tool is characterized in that the air exit channel includes a flow-guiding incline disposed on one side of the compartment, which faces the cylinder, and connected with the entire rim or a part of the rim of the air exit channel, and that the cross section of the air incoming end is larger than the cross section of the air outgoing end.
 2. The pneumatic tool according to claim 1, wherein a curvature of the flow-guiding incline gradually increases from one side thereof, which is far away from the air exit channel, toward the air exit channel.
 3. The pneumatic tool according to claim 2, wherein the flow-guiding incline is connected with a part of the rim of the air exit channel, and the air exit channel further includes a blocking member disposed at a region of the air exit channel, which is not connected with the flow-guiding incline.
 4. The pneumatic tool according to claim 3, wherein the flow-guiding incline and the blocking member are respectively disposed at two opposite sides of the air exit channel.
 5. The pneumatic tool according to claim 4, wherein the pneumatic assembly includes a pneumatic wheel, a transmission shaft connected with the pneumatic wheel and penetrating the housing, and an application tool installed at one end of the transmission shaft, which is far away from the housing.
 6. The pneumatic tool according to claim 5, wherein the application tool is a grinding wheel, a polishing wheel, or a sanding wheel pad.
 7. The pneumatic tool according to claim 5, wherein the axis of the application tool coincides with the axis of the transmission shaft.
 8. The pneumatic tool according to claim 5, wherein the axis of the application tool separates from the axis of the transmission shaft. 